Fences that are used in various sports, such as equestrian sports, consist generally of one or more horizontally extending poles that are supported at each end by vertically extending standards. The pole or poles may be supported by, for example, rigid posts or by empty barrels. Such poles must be supported in such a manner that a light contact will not necessarily displace the bar from the support. In order not to injure the horse or rider, a firm contact should displace the bar. If the support should be too rigidly held, the contact of the horse might result in severe injury to horse and rider.
Equestrian practice jumps are typically created out of wood or plastic such as polyvinyl chloride (PVC). These jumps consist of a solid base and a post or "upright" that extends upwardly from the base. A rail is sandwiched horizontally between two height standards and affixed to jump cups attached to the standards. Typically, the upright portion of the jumping standard is a predetermined height.
Portable obstacles are well known in the art. For example, U.S. Pat. Nos. 3,514,062, issued to Gordon in May, 1970; 4,239,168, issued to Colonna des Princes in December, 1980; 4,368,875, issued to Weiss et al. in January, 1983; 4,793,288, issued to Hoadley in December, 1988; 4,946,139, issued to Tomellini in August, 1990; and 4,989,821, issued to Wong in February, 1991, all disclose various portable obstacles and components associated with their construction and use.
Recent equestrian competitions have asked riders to negotiate "corner" obstacles. When viewed from above, a corner obstacle, is arranged in the shape of an open triangle. In cross-country competitions the preferred construction is that of very heavy solid materials, i.e., railroad ties or telephone poles. Consequently, the obstacle (e.g., a railroad tie) will not be displaced if the horse makes contact with it. Therefore, in order to prepare a horse to jump these solid obstacles in competition, it is necessary to construct practice obstacles that can be displaced when contacted by the horse.
In U.S. Pat. No. 4,368,875 to Weiss et al., metal and wood components with pin locking mechanisms to adjust jump heights are taught. Weiss discloses predetermined height standards with vertical holes in which jump cups are placed to raise and lower the height of the horizontal poles. However, Weiss et al. do not provide suitable structure to create a corner with two poles meeting in the same cup, and without the standard extending above the poles.
U.S. Pat. No. 4,989,821 to Wong teaches an alternative method wherein the standard remains at a predetermined height, but with the cup adjustable for various heights. Wong teaches that two poles may be used between the same two standards. However, Wong's two poles cannot create a corner since they cannot rest in the same cup. Rather, two poles may be used which are parallel to each other or one above the other.
U.S. Pat. No. 4,793,288 to Hoadley makes use of PVC in the construction of its obstacle. However, Hoadley's obstacle is designed for dog agility competitions, and does not teach connecting poles in a triangle formation to create a corner. Hoadley's structure appears to be limited to a high jump formed from vinyl siding and adapted for canine competition. The high jump has a straight vertical face and is not suitable to create the angle necessary for an equestrian corner obstacle.
U.S. Pat. No. 4,946,139 to Tomellini teaches the use of PVC for the construction of equestrian fences. Tomellini's standards, however, are not adjustable. Additionally, it would be impossible to create a corner obstacle with this design, without having the standard above the height of the pole. This results in a potential hazard if the horse were to contact the standard while attempting to jump the edge of the corner.
U.S. Pat. No. 3,514,062 to Gordon describes a conventional jump cup. Gordon's design has proven very useful and is widely used in all fields of the equestrian sports. However, Gordon fails to take into consideration the need for construction of corner jumps. A corner jump requires a cup capable of holding two poles. Gordon's jump cup is designed specifically to hold one pole.
Consequently, there exists an unsatisfied need for a movable corner obstacle that is made of lightweight, durable, and weatherproof materials.